The root canal is a channel in the tooth that runs from the crown to the root in a normal tooth and that contains pulp, which is composed of connective tissue, nerves, and blood vessels. If the pulp is damaged by disease, trauma, or invasion of decay, a root canal treatment is recommended to avoid tooth loss. Treatment typically involves removal of irritants, necrotic tissue, and infected material from the root canal, enlarging and sanitizing the canal, and finally the sealing the canal. The sealing generally is followed with a post canal treatment such as a crown.
In such endodontic treatment, sealers and filling materials are sometimes placed directly on or against vital tissues. Accordingly, it is highly desirable that a material that is used for such a filling or sealing purpose be highly biocompatible. Currently, zinc oxide-eugenol, glass ionomers, amalgams, composite resins, and mineral trioxide aggregates (MTA) are used for root-end and perforation repair. Of these, MTA is currently thought to be one of the more biocompatible materials; see Hauman C. H. J., Love R. M., Biocompatibility Of Dental Materials Used In Contemporary Endodontic Therapy: A Review. Part 2 Root-Canal Filling Materials, Int. Endod. J. 36:147-160 (2003).
Apexification is an endodermic procedure that is related to the root canal procedure. In the apexification, a non-vital tooth with an open apex is filled with an interim filling material to control infection and to enable closure of the apex so that a definitive root canal treatment can be formed at a later time. Calcium hydroxide historically has been used to establish apical closure and to avoid surgery in the apexification procedure; see Frank, A., Therapy For The Divergent Pulpless Tooth By Continued Apical Formation, J. Am. Dent. Ass. 72:87-93 (1966). Calcium hydroxide is effective, but requires high patient compliance and multiple appointments extending over a long period of time. Additionally, in connection with calcium hydroxide treatment, susceptibility to coronal leakage and fracture of the root has been reported; see Weisenseel J. A. et al., Calcium Hydroxide As An Apical Barrier, J. Endod. 13:1-5 (1987) and Schumacher J. W., Rutledge R. E., An Alternative To Apexification, J. Endod. 19:529-531 (1993). A number of studies demonstrate that MTA is effective in apexification procedures; see Kratchman, S., Perforation Repair And One-Step Apexification Procedures, Dent. Clin. N. Am. 48 291-307 (2004); Giuliani V. et al.: The Use Of MTA In Teeth With Necrotic Pulps And Open Apices, Dent. Traumata. 18(4):217-21 (2002); Shabahang, S., Torabinejad, M., Treatment Of Teeth With Open Apices Using Mineral Trioxide Aggregate, Pract. Periodont. Aesthe. Dent. 12(3):315-320 (2000). MTA, however, has poor handling properties relative to calcium hydroxide, including long hardening times and a consistency that some deem too dry for delivery by injection.
The invention seeks, in certain embodiments, to provide endodontic materials and methods useful for root canal and/or apexification procedures.